Recently we found Paul Madary's blog post about digital signatures in a Univeral Application (UWP) with iText 7, and we wanted to share it. Paul gracefully agreed to let us do that, and as a bonus we upgraded the code to be usable out-of-the-box with iText 7.1.3. The only change needed is the method SignDocumentSignature.

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There are several XML Worker examples involving Asian languages on the official iText web site. They parse an XHTML file containing Chinese characters, but it should be easy to adapt them to Vietnamese examples.

The first thing you need, is a font that supports Vietnamese characters. That's something iText can't help you with. In your HTML file, you've defined Helvetica, but that's a standard Type1 font that is never embedded when using iText and that doesn't know how to draw Vietnamese glyphs. That's never going to work.

The first example D07_ParseHtmlAsian will automatically search for a font named MS Mincho. If it finds that font (for instance because you have msmincho.ttc in your Windows fonts directory), the font will show up in your PDF. See hero.pdf. If it doesn't find a font with that name, then the glyphs won't be visible, because you didn't provide any font program for those glyphs.

The second example D07bis_ParseHtmlAsian offers a workaround in case you don't have MS Mincho anywhere. In that case, you have to use an XMLWorkerFontProvider and register a font that can be used instead of MS Mincho. For instance: we use a font stored in the file cfmingeb.ttf and assign the alias MS Mincho:

Why isn't the Rupee symbol showing?

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